P0687

DTC P0687

CIRCUIT DESCRIPTION
The powertrain relay is a normally open relay. The relay armature is held in the open position by spring tension. Battery positive voltage is supplied directly to the relay coil and the armature contact at all times. The engine control module (ECM) supplies the ground path to the relay coil control circuit via an internal integrated circuit, called an output driver module (ODM). One ODM output control is configured to operate as a low side driver for the main relay. The low side driver for the main relay also incorporates a fault detection circuit, which is continuously monitored by the ECM. When the ECM commands the ODM low side driver to turn ON, the expected voltage on the relay coil control circuit should be a low voltage condition. DTC P0687 indicates a short to battery positive voltage, or ignition 1 voltage, on the main relay coil control circuit. If the fault detection circuit measures a high voltage condition, DTC P0687 will set.

DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC P0687 Computers and Control Systems Ignition Relay Control Circuit High Voltage

CONDITIONS FOR RUNNING THE DTC
- The battery voltage is between 9-16 volts.
- The ignition switch is turned ON.
- DTC P0687 runs continuously when the above conditions are met.

CONDITIONS FOR SETTING THE DTC
- The ECM detects a higher than expected voltage on the relay coil control circuit.
- The above condition is present for more than 200 milliseconds.

ACTION TAKEN WHEN THE DTC SETS
- The control module stores the DTC information into memory when the diagnostic runs and fails.
- The malfunction indicator lamp (MIL) will not illuminate.
- The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
- The driver information center, if equipped, may display a message.

CONDITIONS FOR CLEARING THE DTC
- A current DTC Last Test Failed clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
- Clear the DTC with a scan tool.

DIAGNOSTIC AIDS
- The powertrain relay will remain powered up for 15 seconds after the ignition switch is turned OFF.
- This diagnostic table assumes that the vehicle battery is fully charged. Refer to Battery Inspection/Test. Battery Inspection/Test

TEST DESCRIPTION

Step 1 - Step 5:

Step 6 - Step 12:

Step 13 - Step 19:

The number below refers to the step number on the diagnostic table.
2. The engine will crank but will not run with a short to battery positive voltage, or a short to the ignition 1 voltage on the powertrain relay coil control circuit.